Question

我有连接继承的实体：

力撑

@Entity
@Inheritance(strategy=InheritanceType.JOINED)
@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "supporterType")
@JsonSubTypes({
    @JsonSubTypes.Type(value = PersonSupporterEntity.class, name = "PERSON"),
    @JsonSubTypes.Type(value = CompanySupporterEntity.class, name = "COMPANY")
})
@DiscriminatorColumn(name="supporter_type")
@Table(name = "supporter")
public class SupporterEntity extends UpdatableEntity {
    private long id;
    private SupporterType supporterType;
    private PartnerEntity partner;
...
}

PersonSupporter

@Entity
@DiscriminatorValue("PERSON")
@Table(name = "person_supporter")
public class PersonSupporterEntity extends SupporterEntity {
...
}

CompanySupporter

@Entity
@DiscriminatorValue("COMPANY")
@Table(name = "company_supporter")
public class CompanySupporterEntity extends SupporterEntity {
...
}

我有另一个引用SupporterEntity的实体

@Entity
@Table(name = "contact")
public class ContactEntity extends UpdatableEntity {

    private long id;
    private SupporterEntity supporter;
...
    @ManyToOne // same error with @OneToOne
    @JoinColumn(name = "supporter_id", referencedColumnName = "id", nullable = false)
    public SupporterEntity getSupporter() {
        return supporter;
    }
...
}

存储库

@Transactional
@RepositoryRestResource(collectionResourceRel = "supporters", path = "supporters")
public interface SupporterEntityRepository extends JpaRepository<SupporterEntity, Long> {

    @Transactional(readOnly = true)
    @RestResource(path = "by-partner", rel = "by-partner")
    public Page<SupporterEntity> findByPartnerName(@Param("name") String name, Pageable pageable);
}

@Transactional
@RepositoryRestResource(collectionResourceRel = "person_supporters", path = "person_supporters")
public interface PersonSupporterEntityRepository extends JpaRepository<PersonSupporterEntity, Long> {

}

@Transactional
@RepositoryRestResource(collectionResourceRel = "company_supporters", path = "company_supporters")
public interface CompanySupporterEntityRepository extends JpaRepository<CompanySupporterEntity, Long> {

}

@Transactional
@RepositoryRestResource(collectionResourceRel = "contacts", path = "contacts")
public interface ContactEntityRepository extends JpaRepository<ContactEntity, Long> {

    @Transactional(readOnly = true)
    @RestResource(path = "by-supporter", rel = "by-supporter")
    public ContactEntity findBySupporterId(@Param("id") Long id);
}

我使用Spring Boot，Spring Data REST，Spring Data JPA，Hibernate，Jackson。当我尝试使用这样的帖子请求创建一个新的ContactEntity时：

{
   "supporter":"/supporters/52",
   "postcode":"1111",
   "city":"Test City 1",
   "address":"Test Address 1",
   "email":"test1@email.com",
   "newsletter":true
}

我得到了这个例外：

Caused by: com.fasterxml.jackson.databind.JsonMappingException: Unexpected token (VALUE_STRING), expected FIELD_NAME: missing property 'supporterType' that is to contain type id  (for class com.facer.domain.supporter.SupporterEntity)
 at [Source: HttpInputOverHTTP@4321c221; line: 1, column: 2] (through reference chain: com.facer.domain.supporter.ContactEntity["supporter"])
at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:148) ~[jackson-databind-2.4.4.jar:2.4.4]

经过2天的调试我发现了一种方法，但我猜对了。所以，如果我这样张贴：

{
   "supporter":{
      "supporterType":"PERSON",
      "id":"52"
   },
   "postcode":"1111",
   "city":"Test City 1",
   "address":"Test Address 1",
   "email":"test1@email.com",
   "newsletter":true
}

它有效，但我不知道为什么。其他请求有什么问题？当引用的实体没有继承时，它就像其他地方一样。

Answer 1

使用RelProvider：

的另一种解决方法

请勿使用@JsonTypeInfo

为RelProvider子类

创建SupporterEntity

@Component
@Order(Ordered.HIGHEST_PRECEDENCE)
public class SupporterEntityRelProvider implements RelProvider {

  @Override
  public String getCollectionResourceRelFor(final Class<?> type) {
    return "supporters";
  }

  @Override
  public String getItemResourceRelFor(final Class<?> type) {
    return "supporter";
  }

  @Override
  public boolean supports(final Class<?> delimiter) {
    return org.apache.commons.lang3.ClassUtils.isAssignable(delimiter, SupporterEntity.class);
  }
}

另见：

Answer 2

看起来像杰克逊的问题。具体而言，它是com.fasterxml.jackson.databind.deser.SettableBeanProperty中的以下代码：

if (_valueTypeDeserializer != null) {
   return _valueDeserializer.deserializeWithType(jp, ctxt, _valueTypeDeserializer);
}
return _valueDeserializer.deserialize(jp, ctxt);

如果没有继承，则会调用_valueDeserializer.deserialize，而后者会运行一些Spring代码将URI转换为Supporter。

当继承_valueDeserializer.deserializeWithType被调用时，vanilla Jackson当然需要一个对象，而不是URI。

如果supporter可以为空，您可以先POST到/contacts，然后PUT支持者的/contacts/xx/supporter URI。不幸的是，我不知道任何其他解决方案。

Answer 3

您应该能够通过在属性/方法级别设置@JsonTypeInfo（use = JsonTypeInfo.Id.NONE）来解决此问题，例如

试试这个：

@ManyToOne // same error with @OneToOne
@JoinColumn(name = "supporter_id", referencedColumnName = "id", nullable = false)
@JsonTypeInfo(use= JsonTypeInfo.Id.NONE)
public SupporterEntity getSupporter() {
    return supporter;
}

POST POST新实体时如何在Spring Data REST中引用具有继承的实体？

3 个答案: